My laboratory has been involved in studies concerning the regulation of bacterial growth and division. Our approach has been to isolate and characterize mutants of Bacillus subtilis defective in various aspects of the cell cycle. We have discovered mutants defective in: DNA replication, genome segregation, cell surface growth, and cell division; minicell-producing mutants, and recently others able to grow as unusual helical organisms. An analysis of the latter has led me to formulate a new model of cell surface organization and growth in bacteria. Furthermore, during this past year (76/77) I discovered a method which permits the construction of highly organized helical multicellular bacterial forms. These new structures provide an opportunity to study number of higher-order processes hitherto impossible to investigate in bacterial cells. Plans for the immediate future include: 1) detailed studies of the cellular structure of the new bacterial macrobe, 2) explorations of the embryology of macrobe production, 3) genetic studies to include further elaboration of the complexity of the bacterial macrobe, 4) studies of phage infection in bacterial macrobes and 5) studies concerned with testing the generality of my new model of cell surface organization and growth. The objectives of these studies are to gain further insight concerning the regulation of cell growth and division and to establish the first highly organized multicellular bacterial macrobe as a unique model system in which various aspects of multicellularity may be studied.